ᐅ Convert solar thermal system for hot water to photovoltaic system?
Created on: 30 May 2023 15:35
H
hanghaus2023H
hanghaus202330 May 2023 15:35Hello forum members,
I currently have a solar thermal system on the roof that heats water when the sun is shining, designed for six people.
In a few weeks, a photovoltaic system (11.3 kWp) will be installed. The solar thermal system is over 20 years old and will be removed. In the future, the photovoltaic system will also be used for water heating.
A 300-liter (79-gallon) water tank is already in place. It is equipped for the solar thermal system.
My question is: how can the water tank be modified so that the photovoltaic system takes over the function of the solar thermal system?
In my opinion, a controller and an electric heating element are required for this.
Thank you very much for your help.
Best regards from hanghaus2023
I currently have a solar thermal system on the roof that heats water when the sun is shining, designed for six people.
In a few weeks, a photovoltaic system (11.3 kWp) will be installed. The solar thermal system is over 20 years old and will be removed. In the future, the photovoltaic system will also be used for water heating.
A 300-liter (79-gallon) water tank is already in place. It is equipped for the solar thermal system.
My question is: how can the water tank be modified so that the photovoltaic system takes over the function of the solar thermal system?
In my opinion, a controller and an electric heating element are required for this.
Thank you very much for your help.
Best regards from hanghaus2023
R
RotorMotor30 May 2023 15:54What type of heating system do you use?
H
hanghaus202330 May 2023 16:27I still have a gas condensing boiler.
R
RotorMotor30 May 2023 16:52If this situation continues for a longer time, it might be worth adding a domestic hot water heat pump first. It is significantly more efficient than an electric immersion heater.
X
xMisterDx30 May 2023 19:56How much does a domestic hot water heat pump cost compared to an electric heating element?
Y
Ytong202331 May 2023 06:33300 liters (79 gallons) is completely oversized for 6 people and clearly a waste of money.
If the residents don’t spend hours showering, half that capacity is more than enough. I have a 500-liter (132-gallon) hot water storage tank for my 9 apartments, and the heating engineer wanted to reduce it to 300 liters (79 gallons). Keep in mind, that’s for 9 rental units.
For 3 people, I use an 80-liter (21-gallon) electric water heater. It simply plugs into a socket. Before it, I installed a basic analogue timer switch costing about 1.99 euros, acting as a simple control. The water heater is heated daily between 10 a.m. and 3 p.m.
This way, from March to October, my photovoltaic system heats the hot water. From November to February, only partially. The 80 liters (21 gallons) require around 3 kWh of electricity per day to heat up to 70°C (158°F). The tank hardly ever cools down. At an electricity price of 40 cents, I draw power from the grid for about 120 days per year, which is 1.20 euros daily. That results in annual hot water costs of roughly 150 euros, with very low initial investment. I also don’t need a circulation pump.
Of course, a heat pump could be installed, but the investment costs are considerably higher.
If the residents don’t spend hours showering, half that capacity is more than enough. I have a 500-liter (132-gallon) hot water storage tank for my 9 apartments, and the heating engineer wanted to reduce it to 300 liters (79 gallons). Keep in mind, that’s for 9 rental units.
For 3 people, I use an 80-liter (21-gallon) electric water heater. It simply plugs into a socket. Before it, I installed a basic analogue timer switch costing about 1.99 euros, acting as a simple control. The water heater is heated daily between 10 a.m. and 3 p.m.
This way, from March to October, my photovoltaic system heats the hot water. From November to February, only partially. The 80 liters (21 gallons) require around 3 kWh of electricity per day to heat up to 70°C (158°F). The tank hardly ever cools down. At an electricity price of 40 cents, I draw power from the grid for about 120 days per year, which is 1.20 euros daily. That results in annual hot water costs of roughly 150 euros, with very low initial investment. I also don’t need a circulation pump.
Of course, a heat pump could be installed, but the investment costs are considerably higher.
Similar topics